1. Field of the Invention
The present invention relates to a wireless local loop system and method for wireless link control for setting up a wireless link for communication between a wireless subscriber unit of a subscriber and a wireless base station connected to a wireless base station controller.
A wireless local loop (WLL) system connects subscribers scattered over different regions with wireless base stations through wireless links so as to enable communication between subscribers, including ones using ordinary wire telephones, without laying cables between line exchanges and the subscribers. More efficient operation of such a wireless local loop system is desired.
2. Description of the Related Art
As will be explained later in more detail with reference to the drawings, in a WLL system of the related art, the wireless subscriber units detect the normality of the wireless base stations by monitoring the reception levels. When the reception level drops or a link is disconnected, it is possible to switch over to another wireless base station. If a fault occurs at the link side while a wireless base station is still able to send and receive wireless signals, communication with the wireless base station controller side is disabled. Therefore, even if the reception level of the broadcast information or other signal, at the wireless subscriber unit, is normal, communication is disabled while leaving the cause unknown and thus the quality of service is deteriorated. This is the problem.
An object of the present invention is to provide a wireless local loop system including wireless base stations each can notify the wireless subscriber units of the occurrence of a fault and its recovery to enable switching to another stand-by wireless base station and thereby avoid a deterioration of the quality of service.
To attain the above object, according to the present invention, there is provided a wireless local loop system including wireless base stations each provided with a detecting means for detecting a fault between it and a wireless base station controller and a means, when detecting a fault by the detecting means, for adding blocking information to broadcast information and sending the same. The wireless local loop system further including wireless subscriber units, for setting up wireless links with the wireless base stations, each provided with a switching means, when receiving and recognizing the blocking information, for switching the setting of the stand-by station to a wireless base station of a nearby area, whereby a new stand-by station is established by a wireless base station which is able to start communication through a wireless link by the blocking information of the occurrence of a fault, which blocking information can be received since the reception level does not fall or the link is not disconnected.
Therefore, it is possible to avoid a drop in the quality of service at the time of occurrence of a fault in a WLL system.